#include<stdio.h>

int hnt(int n);
int main(int argc, char *argv[])
{
	int n;
	int ans;
	scanf("%d", &n);
	ans = hnt(n);
	printf("%d\n", ans);

	return 0;
}

int hnt(int n){
	if(1 == n){
		return 1;
	}else{
		return hnt(n-1) + 1 + hnt(n-1);
	}
}
